Refactor some of the transformations to the immunity gap
Refactor some of the transformations to the immunity gap

Refactor some of the transformations in the lodash chain that were used
on the Immunity Gap data so that they can be reused to generate the
series for the Missed Children stacked column chart.

unicef/rhizome,SeedScientific/polio,unicef/rhizome,unicef/polio,unicef/rhizome,unicef/rhizome,SeedScientific/polio,SeedScientific/polio,unicef/polio,SeedScientific/polio,unicef/polio,SeedScientific/polio,unicef/polio